Disclosed is a magnetic disk which has a lubricant layer with excellent heat resistance and high adhesiveness and is free from fly-stiction failure or corrosion failure even at an extremely low flying height of 10 nm or lower. Also disclosed is a magnetic disk which has a lubricant layer with good thermal properties and can exert a stable action over a wide temperature range. The magnetic disk comprises a substrate (1), and a magnetic layer (3), a carbon-containing protective layer (4) and a lubricant layer (5) provided on the substrate (1), wherein the lubricant layer (5) contains a magnetic disk lubricant comprising a compound having a phosphazene ring and two or more hydroxyl and/or carboxyl groups in the molecule.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A magnetic disk having a magnetic layer, a carbon-based protective layer, and a lubricating layer over a substrate, wherein: the magnetic disk is adapted to be mounted in a magnetic disk apparatus of a load unload system having a magnetic head flying height of 10 nm or less, and the lubricating layer contains a phosphazene compound represented by a general formula (I), the phosphazene compound having a phosphazene ring (in the formula, at least one of R 1 to R 6 is a group having a perfluoropolyether main chain represented by —(O—C 2 F 4 )m-(O—CF 2 )n- (m and n are each an integer of 1 or more) and at least two carboxyl groups in the perfluoropolyether main chain, and the remaining of R 1 to R 6 are respectively fluorine-containing groups, and three or more carboxyl groups are present in one molecule of the phosphazene compound).
2. A magnetic disk according to claim 1 , wherein a number-average molecular weight (Mn) of the phosphazene compound is 300 to 7000.
3. A magnetic disk according to claim 1 , wherein m+n in the —(O—C 2 F 4 )m-(O—CF 2 )n- falls within a range of 2 to 80.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
January 22, 2007
November 16, 2010
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